Why does Blender 2.70 not stay in Orthographic view when rotating from, say, Front Ortho view?
In blender 2.70 Auto Perspective is turned on be default in the user preferences. This will cause you to go from perspective to orthographic when changing from the User View a view like the side view. The same is true visa versa.

To change this behaviour you can edit the user preferences.


Open the user preferences, Ctrl Alt U
In the Interface tab disable Auto Perpective
To make this change permanent Save User Preferences